Hi all, Doing some research... Have read tons of stuff about adapting a 700r4 to the Pontiac BOP, early Pontiac blocks with adapters, etc, etc... But my main concern that was mentioned but not elaborated on was the size of the 700r4 trans and that the tunnel would have to be hammered to get it in a 55-57 Pontiac. Is that true? The original hydro is pretty big, but I don't have any measurements for the 700r4. I will be running a 455 (400 block - stroked). Not a really high HP motor. Just a cruiser with a fair amount of torque. Iron heads (for now) with an Edelbrock performer intake, cam. It should be close to 400hp and around 450lbft of torque. So my question are: 1. Will the 700r4 fit in the 57 Pontiac with no tunnel mods? 2. Would I be better to go with a built up 200-4r? Any input would be appreciated. Thanks.
I put in a 200-4R in my Skylark. Didn't need to adapt anything as the trans had both BOP and Chev bolt patterns. I had a shift kit put in when it was rebuilt. Mind you, I'm only putting out about 320 HP.
Did your Skylark have the "4 speed Hydramatic"? Pontiac calls them the Dual Coupling Hydramatic/Super Hydramatic. Oldsmobile called them the "Jetaway". Not sure what Buick had at the time.
The original 347 has a unique bolt pattern. Only two automatics will fit without an adapter, early dual range hydro and dual coupling hydro. Now if you are going to 400/455, which has a BOP pattern, then you have more choices. You could go with turbo 350 or turbo 400 with BOP bell housing. This is not an overdrive unit, but will work. The 2004r has the dual patterned bell housing and will bolt up too. The 700r4 has a Chevy bell pattern, so an adapter would be needed to adapt to BOP pattern. This would be costly. There are a couple of older transmissions that would work too. Roto 10 slim jim or dual coupling hydramatics from 1964 Pontiac. But these are old transmissions and frankly not the best transmissions. Hope this helps
As stated in my first post, for the record... I will be using a 455 (stroked 400). So it has the BOP bell pattern. My question is whether a 700r4 or 200-4r actually fits within the tunnel of a 55-57 Pontiac without beating up the tunnel. Has anyone actually done it to a 55-57 Pontiac? Thanks.
If it helps any, the 57 engine has top two bell bolts that are same as top two BOP pattern. You might take the old transmission and do measurements from these holes, then compare to 2004r, 350, or 400. The 700r4 will need an adapter, so unless you know someone with the adapter that you can use to get measurements you might have some difficulties.
I am going to offer a comment that STILL DOES NOT answer your initial question, but may be useful , nonetheless. It is stated in post #6 that the 700R4 has a Chevy pattern and requires an expensive adapter. This only partially accurate. It is true the 700R4 has a Chevy bolt pattern and needs and adapter plate, but IT IS NOT expensive. The locating dowels and lower bolts of both Chevy and BOP pattern are in the same location. there is a thin (1/4" to 3/8") plate that is used between the engine and trans that has the dual pattern and accommodates bolting them together. These are readily available form several sources. At most you may need same dimension spacers between the torque converter lugs and the drive plate (Flywheel/flex plate). Since the drive plate location does not change and the starter bolts to the block, no other adapters are needed. Depending on which side the starter is, it may require a suitable lower cover for the flywheel/torque converter.
im intrested of this.tunnel clearence? but still no one that acctually have done this on a 55-57 pontiac?i have 1958 gmc 1962 catalina(tunnel work) cadillac 1949,all with 700r4 trans.all with engine in org position.(posted here on hamb) as stated the thin adapter plate for 64-79 pontiac engine is between 50-100 dollar and using org starter bolt make a overdrive easy swap. i dont want to reevent the wheel again. pic is 1967 400 with 700r4 home made adapter and mid engine mount ken sweden
Hnstray - Thanks. I have read about the adapters for the Chevy to BOP. You are right... actually pretty cheep and very simple. Most come with spacers/matching washer for the torque converter. swe64 - I am sure it has been done to a 55-57 Pontiac passenger car. I cannot remember where I read it, but someone (either on this board or the PY board) stated he will likely "have to beat up the tunnel on his 55 to make the 700r4 to fit." But I cannot remember who that was or even if he actually installed the 700r4. The post was a few years old. BTW - I have read your stuff - awesome work on your adapter and install. I really like how you used the adapter as a engine mount also! Anyway... thanks for the reply. Bolting the motor/adapter/trans is no problem. The adapters are only around $65 bucks for the cheaper ones to to around $120 plus for a more expensive versions. So, if someone has actually done a 700r4 install to a 55-57 Pontiac passenger car I would like to hear about it. And any issues with fitment in the tunnel and shifter linkage?
I know it’s an old thread but I am interested in doing a 4l80e or th350 in a 57 safari. Anyone done this in a 57 Pontiac?? Does the tunnel need to be modified? I understand something about the trans mount/motor mount maybe involved? Sent from my iPhone using The H.A.M.B. mobile app
5 year old thread but in the event you still haven't got your 57 on the road: I had a 55 with a later Pontiac v/8 and a 350 turbo. No work needed to be done on the tunnel for the 350 trans and I believe a 2004R is very similar to the 350 trans.
The tunnel "should" fit. Since the car was designed for the Hydramatic (NOT turbo hydramatic, ie NOT TH350 or TH400). The Hyrdramatic is a completely different trans, but is somewhat large. A 4l80e, I believe, is a large trans. Not sure how it compares to a Hydramatic. Mounting of the original Hydramatic is done with two "bell mounts" on each side of the bell housing and a single "chin mount" for the motor itself. It is the triangle mount in reverse compared to more modern mounting. Adapting a 347 to a more modern trans will require adapters due to different bell bolt patterns. I will try to upload pictures that explain what is said.
Here is a pic showing a Hydramatic compared to a TH400. On the old crusty Hydramatic you can see the bell mounting to the frame. The frame is a 57 Pontiac convertible.
Here is another view. I clipped a 57 convertible frame with a firebird sub frame. I plan on using a TH400. I don't have the measurements on hand, but the TH400 will fit where the Hydramatic once lived. You will need to fab a rear trans mount for the modern trans (TH350/TH400/4fl80e)... You will also need to come up with something other than the "chin mount" for the 347. I actually adapted some "bell mounts" from a Tri-Chev to work with the old style "chin mount" if I use an older motor such as a 347.
I didn’t want to hijack a thread but no need to start another one. That’s what I am talking about!! Great info ClassicDriver. You think it’s possible without taking the body off the frame?? Wilcap trans adapter should do it. But he said the motor mounts might be tricky. Can I take 57 Chevy type mounts and fab them to work or start from new?? Sent from my iPhone using The H.A.M.B. mobile app
Opps. I see the “adapter some “bell mounts” from a 57 Chevy” Thanks Sent from my iPhone using The H.A.M.B. mobile app
Oh... btw. I messed up the pictures. The modern trans you see in the pic of POST 18 and top pic of POST 19 are a TH400. The other pics show a TH200-4r. Sorry. But you get the idea. The TH400 is not much bigger. See the following pictures with more info..
Yes... I do think it is possible without taking the body off, if you are talking about making the bell mounts.... I used the Danchuk parts seen in the previous post and modified them for the BOP (Buick Oldsmobile Pontiac) bolt pattern, which you would not have to do if using the Chev pattern! However there is a small complication. The original bell mounts are actually bolted to a cross member that is bolted the frame itself. You will need to modify that cross member to allow room for the new trans (TH350/TH400/4l80e/etc..). These modern trans interferes with the cross member when it runs under the trans. The original Hydramatic has a gap that the cross member runs through. I have seen some guys just remove the cross member all together, but it is a pretty beefy unit and I feel it adds to the frame strength and stiffness. See pics of modified cross member. (It was fully welded after these pics were taken) As far as the trans adapter from Wilcap (or Bendtsen), I don't think that would be much of a problem. You would just have to adjust the mounting rearward to accommodate the added thickness of the adapter plate.
Great fab work and thanks for the info. Looks do-able. Sent from my iPhone using The H.A.M.B. mobile app
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